This invention relates to an apparatus for winding a continuous web of film material onto a core driven in rotation by a spindle and onto which said web of film is wound in order to form a cylindrical wound roll by means of a train of lay-on rolls for applying said web to a said core, said train comprising first and second idling rolls arranged parallel to said core the first of said rolls being partially surrounded, during winding of said core, by said web and being disposed tangentially with respect to said second roll while firmly pressing said web against the surface thereof, and with respect to the outer surface of the wound roll to which said film is applied.
Very numerous winding devices are known in the art, such apparatus being used for winding thin webs of materials such as paper, plastic material which are supplied to users in roll form wound onto cylindrical cores which are generally of cardboard. When extremely thin webs are involved in which the material is generally in the form of film or film-like material of a resilient and deformable material such as plastics, it is extremely difficult to achieve regular winding of successive layers the outer surface of which are only truly flat when the film is under tension. Inspection with the naked eye of rolls of such film always reveals the presence of irregularities produced during winding.
Additionally, there is also a need to wind certain plastic materials that have been processed to form thin tear-resistant films into a roll that can be used directly and which is hence brought to the appropriate width after leaving the plastic material film production line.
One of the objects of this invention is hence to provide winding apparatus for a strip of film material for use directly following the material production line and which enables a regularly-wound roll of film to be obtained, in which the winding operations can be initiated and monitored automatically through the use of controlled-pressure lay-on rolls which faithfully follow the growth in diameter of the winding roll in order to achieve regular application of the film onto the outer surface of the winding roll, and which can additionally be regulated in position and withdrawn.
Another object of the present invention is to provide apparatus enabling slit rolls of thin film material to be obtained in a continuous production process through the use of winding apparatus which is highly accurate, robust and ensures that completely reproducible and reliable operation of all its component parts are obtained, leading to a significant reduction in maintenance downtime.
A further object is to increase productions speeds and particularly speed up the operations of thread-up and change of winding from one roll to another while simultaneously obtaining higher product yields and quality.
It is a further objects of the invention to provide winding apparatus which includes a set of feed rolls that cooperate with means for cutting the film and bring it to the appropriate width ahead of the lay-on rolls as well as suitable means for evacuating offcuts after cutting.
A further aim of the invention is to provide a winding method using apparatus which enables the start of winding as well as changeover from one film roll to another to be achieved automatically.